In the food packaging industry, it is a common practice to assemble a cluster of food products (e.g. meat or poultry) which have been individually vacuum packaged in plastic film, and put the cluster into a larger plastic film bag or envelope, which is then gas flushed and vacuum evacuated, to produce a tight fitting, oxygen free, master package. This maintains the fresh quality of the food products during storage and transportation.
The present invention is applicable to this type of master package, as well as to one containing individual unclustered items.
To accomplish evacuation of the gas from the plastic film envelope, a vacuum probe is inserted into the film envelope and the gas is sucked out. One problem encountered with this process, is that the tip of the probe where the vacuum orifices are disposed is pressed against the content of the envelope and becomes clogged and ineffective. These orifices, which may be grooves extending only a short way from the probe tip, become clogged and ineffective by the collapsing plastic film envelope. This occurs because, in conventional practice, the vacuum probe provides a vacuum only at its tip.
Additionally, in the conventional approach the vacuum is applied through the probe inserted into the contents of the envelope, requiring that the envelope have its opening on the top surface of a generally broad and shallow package. This creates an envelope geometry which consumes a relatively large amount of plastic film for the product size.
One variation on the conventional approach is to evacuate a side or end loaded envelope by using a vacuum probe which enters in a horizontal plane. This side-inserted probe encounters the same problem as one inserted from above. As the plastic film envelope collapses around the probe, the grooves or slots at the tip of the probe tend to become blocked by the content of the envelope.
Accordingly, it is an object of the present invention to provide an improved method of evacuating gas from a gas tight envelope without clogging the vacuum probe which is evacuating the gas.
It is a further object of the present invention to provide a method for evacuating gas from a gas tight envelope containing solid material, in which a vacuum probe is utilized in such a manner that the vacuum is applied across substantially the entire face of the probe, tangentially opposing the solid material in the envelope.
Yet a further object of the present invention is to provide a methodology for evacuating gas from a gas tight envelope containing a solid material which avoids potential clogging of the vacuum probe by either by the collapsing envelope or the content thereof.